1. Field of Invention
The present invention relates to an open-end wrench and a method of manufacturing the same, and more particularly to an open-end wrench made of two different materials and a method of manufacturing the same.
2. Related Art
As shown in FIG. 1, a conventional open-end wrench 10 is integrally formed of steel. Although an wrench opening 111 of a head portion 11 thereof is strong enough to screw on or off a screw, and a handle portion 12 thereof has a certain strength to provide enough torque torsion rigidity, an overall weight may be heavy, and especially, when the wrench is used on a large-size screw and is carried, stored, delivered, and used in high altitude operation (such as a telecom tower and a steel truss arch bridge), the wrench is unable to satisfy a light weight requirement of a user. Especially, in a filed where the light weight wrench is required, for example, a drilling platform, wind power generation, pylon, mountain climbing or mountain areas, a conventional pure-steel wrench is usually criticized due to its heavy weight but has to be accepted.
Another problem is that if the open-end wrench 10 is made of light alloy for a light weight, a wrench opening thereof does not have enough strength to screw on or off a steel screw.